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By T. E. Wilson

The length of Alaska's coastline, combined with the presence of a significant number of fjords, encourages consideration of marine disposal of mine tailings. However, the decision-making process is complex because various factors govern the viability of the submarine tailings disposal (STD) option. An expert system, called the Submarine Tailings Disposal Expert System (STADES), was developed to help mining project planners explore the feasibility of STD. A review of the existing literature, supplemented by engineering recommendations, on the various aspects of the marine disposal of tailings formed the knowledge base for the expert system. The shell used to develop the expert system was LEVELS.

Jan 1, 2003

By T. E. Wilson

The length of Alaska’s coastline, combined with the presence of a significant number of fjords, encourages consideration of marine disposal of mine tailings. However, since various factors govern the viability of the submarine tailings disposal (STD) option, the decision making process is complex. An expert system, called Submarine Tailings Disposal Expert System (STADES) that will help mining project planners explore the feasibility of STD, was developed. Existing literature, supplemented by engineering recommendations, on the various aspects of marine disposal of tailings was reviewed and formed the knowledge base for the expert system. The shell used to develop the expert system was LEVEL5®.

Jan 1, 2001

By C Kusi-Manu, E Nyamusika

Geita Gold Mining Limited (GGML) is owned and jointly managed by Ashanti Goldfields Company (Ghana) and Anglogold (South Africa). The mine is currently one of the largest gold producing open pit operations in Africa producing 620 000 ounces of gold and mining in excess of 70 000 000 tonnes of material per annum. The mine currently has 2000 full time employeeÆs and a mine life in excess of 12 years. Geita Gold Mine is comprised of 11 different gold deposits situated in the Lake Victoria Goldfields of North Western Tanzania (Figure 1). The gold deposits are primarily associated with banded ironstone formations within an Archaean greenstone belt. Current global resources, including Inferred, stand at 129.5 million tonnes grading 3.91 g/t (16.2 M oz). Open pit reserves total 70.4 million tonnes grading 4.16 g/t (9.4 M oz). The majority of the gold resource is hosted by the three deposits (Nyankanga, Lone Cone and Geita Hill) within the æGeita TrendÆ a large and continuous (>4 km long) mineralised zone (Adofo, 2002). Geita Gold Mine commenced operations in June 2000, as the second large-scale open pit gold mine in Tanzania. The new workforce of 800 people had no previous experience in open pit gold mining. Since the start of the operation, Geita Gold MineÆs management ambition was to become a world leader in the application of best practice in all technical disciplines and in operational success. Staff development and training was identified as one of the major components in the company achieving its aim. Geita Gold MineÆs management has committed the necessary training staff, resources and the commitment of over $US 1 M a year to staff training and development programs for 2003 and 2004. The process and management of Geita Gold MineÆs mining geology staff training and development program is presented in this paper.

Jan 1, 2003

Jan 1, 1968

By Stanley D. Michaelson, Ben. H. Slothower

The depletion of most high-grade ore reserves coupled with growing demands for metals and fuels has made it necessary to bring into production increasingly lower grade deposits. Improvements in technology have made lower grade ores economically recoverable in spite of major increases in labor and material costs and the initial investments required to open new mines and build their metallurgical and service plants. To remain competitive, managements of mining companies must keep abreast of and exploit these often complex technical developments. The proper application of these improvements in technology requires extensive and detailed study. In addition, managements of mining and other industries are becoming more deeply involved in public affairs and the myriad of other nontechnical problems common to all industries. These involvements, plus the demands of evaluating technological developments as well as the necessary work related to the routine administration of operations, have required mining managements to delegate additional study and review functions to staff services. To help overcome the problems involved in adopting the best technologies, managements have generally expanded their engineering and research staff services. Integrated, base-metal-producing companies, having open pits, concentrators, smelters, and refineries, are generally more research and engineering oriented than are most smaller mining companies and quarries. However, mining methods for even the simplest open pits and quarries are improving rapidly, and installations of these improvements are essential to combat increasing costs. Because of this, the managements of smaller operations may also require enhanced engineering staff services to realize the potential benefits.

Jan 1, 1968

Queensland Mines Limited operates a small uranium treatment plant at Nabarlek in the Arnhem Land Aboriginal Reserve, some 265 km due east of Darwin. It was the wish of the local Aboriginal people that the ore be treated over an eight year period and that no township be constructed in Arnhem Land. Due to these wish- es it was decided to house employees and their families in Darwin and fly the employees to the minesite for work rosters. A singleman's style camp only was constructed at Nabarlek. To satisfy the Aboriginal people's wishes all recreation time is spent offsite thus lead- ing to a roster system whereby employees spend three distinct periods of 6, 6 and 4 days on- site, broken by recreation periods of 3, 4 and 5 days in Darwin, during each 28 day period. Employees are divided into four opposing rosters, which allows at any given time for approximately half the workforce to be onsite and the other half on rest and recreation leave in Darwin. This method of staffing has generally proved to be most satisfactory although at times problems arise, in terms of both product- ion and social effect not normally encountered when operating within more conventional circum- Stances.

Jan 1, 1984

By L Abrahamsson

This paper describes results from a gender study for a new mine in Pajala, a small community in northern Sweden. Using a gender perspective, the study examines migration, education, local culture, the labour market, and work organisation as problems and opportunities in the regional context for the planned mine. The most obvious ‘gender issue’ for the Swedish mining industry is the very low percentage of employed women, which is even lower among mining workers. To recruit the best people, a company actively needs to attract both women and men; however, the mining companies find it difficult to recruit women as cultural, labour market and educational traditions as well as the mining companies’ own cultures often make it difficult for women to find work in the mining industry.The Torneå river valley, the region surrounding Pajala, has a gender-segregated labour market and gender-stereotyped culture and few young women live in this traditional and oldish region. Many young people leave the region and this is especially true for women. Compared to the rest of Sweden, there is a low educational level, especially among the men. In the mining companies, as in many other male homosocial workplaces, the workplace culture has strong connections to a certain type of traditional masculinity (laddishness, a kind of ‘macho-style’) and for a long time this has excluded women. ‘Gender’, however, is not only a question of recruiting women to a male-dominated industry. An organisation that discriminates according to gender can become inflexible, hindering communication, learning, innovations and change processes. In mining companies, this can manifest itself in hesitant attitudes among the miners about safety as well as organisational and technological development.This study found that companies establishing a presence in this region should develop a strategy for how to deal with and manage the risks and opportunities in the surrounding society (the regional culture) as well as inside the company (the mining culture). This need to be strategic will also be required of future mining companies as they will face higher demands on safety, gender equality, and technology to become modern, efficient and lean organisations.

Nov 22, 2011

By D. O. Miller

The effective staffing of personnel in a new concentrator facility is a key factor in the success of the operation. By selectively recruiting quality individuals, a company is in a strong position to build a positive work ethic which will become an integral part of it's culture. And culture, which is a set of standards that all employees work to uphold, is that intangible as- set that often determines whether or not a company will survive during difficult economic times. Recruiting and placement of personnel in a concentrator facility requires an emphasis on planning. Management must carefully analyze the following elements when designing a hiring plan: 1. Number of positions 2. Hiring schedule (timetable) 3. Critical positions 4. Lead-time for trainee posit ions 5. Characteristics of the ideal workforce This presentation will focus on a proven system that is efficient (and yet simple) for achieving a new concentrator facility's manpower requirements. IDENTIFYING THE STAFFING NEEDS As previously stated, the key to staffing is planning. Management will find that a basic manpower chart will provide the hiring schedule to meet deadlines. In fact, this system begins with a manpower chart (Figure 1). The chart basically works in reverse of the hiring requirements: the last scheduled hire is the first job on the list. This approach ensures that the company will not find itself compressed against the facility start-up date. A cardinal rule in recruiting a workforce is to allow sufficient time to orient and train employees to the procedures and culture of the system. Problems in selection of personnel begin when the hiring program is short-circuited for timing reasons. The quality of employee selected invariably suffers accordingly. The second section is the key to the success of the manpower program. This is the latest date by which a formal recruiting effort must begin in order for the hire date to be met. Leadtimes are usually as follows: 1. 90 days for company transfer positions 2. 60 days for experienced new hire positions 3. 30 days for trainee positions

Jan 1, 1986

By M. Soderstrom

In a solvent extraction (SX) plant, stage efficiency calculations are used to determine mixer efficiency. With modern extractants and mixing equipment, it is generally taken for granted that stage efficiencies will be above 95%, but this is not always the case. Dependant on mixer/solution conditions, stage efficiencies can occasionally be low, therefore leading to higher reagent usage. Proper methods to identify when stage efficiency performance is below expectations, and ways to identify if it is an equipment or chemical issue are valuable tools for a plant metallurgist. With these tools and skills an on-site metallurgist can more quickly return their SX plant to proper operation. This paper will discuss methods for analyzing stage efficiency, evaluating factors that may affect stage efficiency, and evaluating the impact of stage efficiency on the overall operation.

Jan 1, 2010

Reduce longwall intake contamination by controlling respirable dust generated by the stage loader. Approach Install a water-powered scrubber on the stage loader immediately outby the crusher. Dusty air from the crusher is drawn through the scrubber and a clean air discharge is delivered into the primary face airflow. How It Works The contamination of intake air is a significant dust control problem often overlooked on many longwall faces. This dust source contributes to the full shift dust exposure of all face personnel, and thus can significantly affect compliance with Federal regulations. Several sources contribute to contamination; however, dust generated by the stage loader crusher is the single largest source. The breaking action of the crusher generates a tremendous quantity of dust, which mixes with the primary ventilation airstream and is carried down the entire length of the longwall face. The installation of a water-powered scrubber (see diagram) has proven effective in controlling crusher-generated dust. The scrubber is mounted immediately outby the crusher. A duct is placed over the scrubber intake and attached to a flanged opening over the crusher discharge. In

Jan 1, 1982

An open pit production planning method for stage mining is presented in this paper. The method brings solutions to the four most important parameters in stage mining : 1) the number of stages, 2) the size and geometry of each stage pit, 3) the mining sequence of the benches in the stage pits, and 4) the time of transition from one stage to the next. The method can also simultaneously optimize the ultimate pit, mine life, and production rate in each stage.

Jan 1, 1996

By D. A. Lucero, J. E. Brockmann, L. A. Mondy, K. L. Rubow, D. J. Rader

"Department of Mechanical Engineering, University of Minnesota, Minneapolis, MNExperimental and correlated stage responses (the fraction of particles entering an impactor that are collected on a stage) are presented for the Andersen Mark III and Marple personal cascade impactors. The impactors were operated upright and fully assembled so that interstage interference and wall losses could be properly studied. The observed stage responses showed maxima that fell significantly short of unity, meaning that a monodisperse aerosol is never collected exclusuvely on one stage, but is distributed among several stages and internal losses. Correlations for the stage responses are presented so that the experimental results can be used to determine size distributions with available data-inversion algorithms. Simulations with log-normal distributions show significant differences between dpa50 histograms and the more accurate distributions that result by taking the response functions into account.Cascade impactors are widely used for the measurement of aerosol size distributions; their ruggedness and simplicity of operation make them an attractive choice for a variety of environments. In one common application, the aerosol of interest is drawn through the impactor, and the amount deposited on each stage is determined gravimetrically. The primary objective is to extract as much information as possible about the initial size distribution from the resulting set of weights. Unfortunately, the reconstruction of contin-uous size distributions from finite data sets is an ill-posed problem. Not surprisingly, a variety of such reconstruction techniques are presently in use; the success of each method depends on the particular nature of the aerosol sample and the instrument response.Inversion of impactor data by any of these techniques requires that the response functions for each stage be known. The stage response function gives the fraction of particles entering the impactor that deposits on that stage. Values of the response function range from zero to one, and depend on impactor operating conditions (e.g., geometry, flow rate, and gas properties) and particle properties (e.g., diameter, density, and shape factor). As interstage interferences and particle losses will affect each stage's response, experimental determination of stage responses should be made for fully assembled impactors. Unfortunately, impactor stage response functions are rarely reported; rather, single-stage efficiency curves are given that provide an incomplete description of impactor performance.This paper presents experimental stage responses for two fully assembled cascade impactors: the Andersen Mark III and Marple personal impactors (model 298, Andersen Samplers, Inc., Atlanta, Ga.). These calibrations were performed with monodisperse liquid droplets for both impactors and also with monodisperse solid spheres for the Marple personal impactor. The calibration results for the Mark 111 impactor presented here have been previously reported in the response-function format (Rader et al., 1989). The calibration results for the Marple personal impactor, however, were originally presented in the single-stage efficiency for¬mat (Rubow et al., 1987) and have been reanalyzed in this work. Losses within both impactors are considered, and their treat¬ment within data inversion techniques is dis¬cussed. In addition, correlations for each impactor's response functions are presented so that these calibration results can be easily included in data-inversion algorithms. Size distribution inversions using these response correlations are compared with the standard cut-point method for two lognormal test dis¬tributions."

Mar 1, 1992

By Malek Smadi, Yazen A. Khasawneh

"New embankments were constructed mostly on soft clays as part of interstate I69 extension in southern Indiana. The embankments serve as bridge abutments and as part of the fill sections along the interstate extension alignment. The height of the embankments range from 50-ft to 125-ft with a maximum foundation thickness of about 75-ft. The foundation soils comprise relatively high compressible fine grained soils. A fully coupled Hydro-Mechanical numerical simulations were conducted for optimizing the construction stages of the embankments. The objective of the staged construction is to allow for sufficient effective stress and undrained shear strength gain to ensure foundation stability under the stage load. Wick drains were utilized to shorten the drainage path and thus accelerate achieving the required undrained shear strength. The extensive field investigation and laboratory testing programs provided a good understanding of the subsurface conditions and allowed the use of a relatively advanced soil constitutive model in the numerical simulations of the staged construction. The effectively designed instrumentation program allowed for monitoring the settlement and pore water dissipation during construction. The pore water pressure, and surface and subsurface settlements from the numerical model predictions reasonably agreed with the instrumentation data over the construction period.INTRODUCTIONThe stability of soft fine grained foundation soils due to embankment construction is dependent on the undrained shear strength of such soils. The permeability, compressibility, and drainage boundaries control the foundation soils response (settlement magnitude and rate) to loading. The settlement magnitude is a function of minerology and soil structure. The settlement rate which is equivalent to the rate of excess pore water pressure dissipation is a function of the soil permeability and drainage boundary. The dissipation rate control the evolution of effective stress and thus the gain of undrained shear strength. As such, if the increase in total applied load is controlled such that enough time is granted for the evolution of the total stresses into effective stresses, then the stability of the foundation soils is enhanced by the gain of the undrained shear strength. The controlled application of the total stress is the definition of the staged construction. From the definition of the staged construction, it is obvious that the process is a coupling of the hydraulic and mechanical responses of the foundation soils."

Jan 1, 2017

By Ken Criley, Marc E. Orman

Identifying the optimum ultimate height for heap leaching ore requires the consideration of a number of competing factors. A primary limitation is the reduction in the permeability of the ore with increasing heap heights. At low permeabilities the heap can blind off, cause serious ponding and runoff, and become very difficult to rinse at closure. The authors present a laboratory methodology that has been successfully used on several projects to identify the maximum height for controlling heap permeability.

Jan 1, 1996

By M. C. Roberts

As nations advance through various stages of economic development, the patterns of demand for minerals change. For example, as a nation develops from a subsistence economy through industrialization and into a service based economy, the use of minerals is at first low, then grows rapidly, and finally stabilizes. The past trends in the use of agricultural minerals by the currently advanced nations provide a pattern that the world as a whole may follow as it progresses through the stages of economic development. Future needs for agricultural minerals are estimated using this approach.

Jan 1, 2001

By Max Pena Woolcott, Winfried Rosenstock, Maria Chappuis, Walther Hennig

"In a Peruvian-German Technical Cooperation project for the Mining Sector the ""Milpo-cut"" along with the electric initiation system has been successfully implemented in a Peruvian metal-ore mine.Specific savings in drill work and explosives consumption up to 50 % have been achieved in headings and slopes. The positive results have motivated further Peruvian mining companies to introduce the new technique."

Jan 1, 1994

By Roswell Johnson

THE prevailing system of wells on a rectangular basis, as shown in Fig. 1-A, has developed because of the exigencies of offsetting at boundary lines. When, however, a very large tract is, being drilled, it is often possible to abandon this inferior method for the superior arrangement C- PROPER STAGGERING FIG. 1.-THREE SYSTEMS OF SPACING WELLS. known as "staggering," which is illustrated in Fig. 1, B and C. The advantages of the triangular over the rectangular method are evident from Fig. 2, computed on the basis of one well to 10 acres (4 ha.). With the triangular system, no land is more than 409.4 ft. (124.8 m.) from a

Jan 8, 1918

Those involved in the mining and minerals industry really are an optimistic bunch. Faced with an economic downturn that has spread across the globe ? one, some say, that crept up on everyone ? mining professionals remain hopeful that the industry will return. An example of that optimism is the attendance at two of the industry?s key conferences and exhibitions. In February, more than 4,200 people attended the SME Annual Meeting and Exhibit in Denver, CO. And a week later, in Toronto, Ontario, more than 18,000 were on hand for the Prospectors and Developers Association of Canada?s (PDAC) meeting. Both are respectable numbers and run contrary to meeting attendance figures during previous downturns when attendance and the numbers of exhibitors fell off significantly. Like other downturns, this most recent one has resulted in massive layoffs, curtailments of production and outright closures. Exploration has been hard hit and many junior mining and exploration companies will either disappear or be swallowed up by others. Gold is its usual self The PDAC generally attracts the gold mining and exploration sectors. So that might explain some of the optimism at the meeting. Unlike base metals and construction materials, gold, not surprisingly, is doing well. And most of the companies in the Investors Exchange at PDAC were involved with gold. While the balance sheets for most base metals companies look bad, gold companies appear to be not as hard hit. Gold is doing what it usually does during a downturn ? act as a safe haven while the value of other assets collapse worldwide. Governments around the world are preparing to pour trillions of dollars in an attempt to resuscitate their economies. This will likely lead to inflation, some experts at the PDAC convention said, which will be good for gold. And gold mining companies are also benefiting from lower production costs. The result is that some gold watchers believe gold could reach $64/g ($2,000/oz) at some point.

Jan 1, 2009

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

Residential and commercial plumbers in the United States were introduced to Viega?s copper press technology in 1999. In short, the technology allows plumbers and installers to join copper pipe securely in four to seven seconds on pipe sizes of 1.2 to 10 cm (0.5 to 4 in.) by pressing the connections with specialized tools and fittings rather than through sodering or welding. The water- and air-tight technology, first introduced in Germany in 1989, includes three different sealing elements, a variety of materials and a selection of configurations. By eliminating the need to thread or solder pipe, connections and repairs can be made quickly and securely. Installations are also much quicker and as secure as traditional methods.

Jan 1, 2012